NEW YORK - Six different types of prescription drugs were found in Heath Ledger's apartment -- including anti-anxiety medications and sleeping pills -- though the cause of his death won't be known for several days after a preliminary autopsy Wednesday was inconclusive, authorities said.

A rolled-up $20 bill was also found on the floor near the Australian actor's bed, but lab tests detected no traces of drug residue. Police also said no illegal drugs were found in the apartment.

Among the prescription medications found were pills to treat insomnia and anxiety, and an antihistamine, according to two law enforcement officials who spoke on condition of anonymity because the investigation is ongoing. Three of the drugs were prescribed in Europe, the sources said.

New York Police Department spokesman Paul Browne said lab tests found nothing to indicate it had been used to snort drugs.

The Australian-born actor was found dead Tuesday by his housekeeper and a massage therapist -- lying naked and face-down on his bed, police said. The pills were found in bottles in Ledger's bedroom and bathroom, and police said the death was caused by a possible drug overdose and appeared to be accidental.

Ellen Borakove, a spokeswoman for the medical examiner's office, said the autopsy on the 28-year-old actor was inconclusive and that more would be known in about 10 days, when more tests were completed.

Police said Ledger probably died Tuesday between 1 p.m. and 2:45 p.m. At 1 p.m., the housekeeper went into his bedroom to change a light bulb, saw him sleeping and heard him snoring.

At 2:45 p.m., the massage therapist showed up for Ledger's appointment, knocked on his door and got no answer. She later noticed Ledger was unconscious and called Mary-Kate Olsen, whose number was programmed into Ledger's cell phone, to seek advice.

Olsen said she would send over her private security. In the ensuing moments, the massage therapist realized that Ledger might be dead, and called 911. Paramedics -- and Olsen's security people -- arrived minutes later.

News of the death stunned family, fans and colleagues.

"Working with Heath was one of the purest joys of my life," said Ang Lee, who directed Ledger in "Brokeback Mountain." ''He brought to the role of Ennis more than any of us could have imagined -- a thirst for life, for love and for truth, and a vulnerability that made everyone who knew him love him. His death is heartbreaking."

Lee Daniels, who produced the critically acclaimed "Monster's Ball" in which Ledger starred, strongly disputed any notion that Ledger had a drug problem.

"The definition of substance abuse is really up to one's perspective," Daniels said. "I didn't see him as a drug addict. I saw him as someone who enjoyed life. I know drug addicts, he was not a drug addict."

He said he saw Ledger a couple months ago and that he was in great spirits. "He was in a good mood, he was in a great place ... he was excited about living in New York."

Before moving to Manhattan, Ledger lived in Brooklyn with then-girlfriend Michelle Williams in a four-story, sage-green brownstone with a black wrought-iron fence. Yellow tulips with red stripes were among the bouquets left by well-wishers Wednesday.

At the Brawta Caribbean Cafe two blocks from the residence, owner Jennifer Ewers said Ledger was a frequent guest who always ordered jerk chicken, rice and beans, and sorrel.

"He was a perfect gentleman. He comes in here with his hoodie on, reads a book, and gives you a peace sign," she said. "He was always with his daughter, playing hide-and-seek among the plants, or on his skateboard, peeking his head in."

Speaking in Australia, Ledger's father called the death "tragic, untimely and accidental."

"Heath has touched so many people on so many different levels during his short life," Kim Ledger said. "Please now respect our family's need to grieve and come to terms with our loss privately."

Fans left flowers and candles Wednesday outside Ledger's apartment in the tony SoHo neighborhood of Manhattan on Wednesday. Khaled Ali, 41, a stage manager for a Broadway show, dropped off a candle on his way to work, saying he and fellow cast members were devastated.

"I felt a connection with him as an actor, as a fellow in the theater community," he said. "With 'Brokeback Mountain' he touched me personally in telling the story of my community. It was very touching."

Ledger was known for grueling, intense roles that became his trademark after he got his start in teen movies like "10 Things I Hate About You." Thereafter, he avoided the easy path in favor of roles that forced him to bury his Australian accent and downplay his leading-man looks: the tormented gay cowboy Ennis Del Mar in "Brokeback Mountain"; a drug addict in "Candy"; an incarnation of Bob Dylan in "I'm Not There."

Playing the Joker in the upcoming Batman movie "The Dark Knight," may be his final finished performance.

Ledger split last year with Williams, who played his wife in "Brokeback." The two had a daughter, the now 2-year-old Matilda. Early Wednesday, Williams and Matilda left Trollhattan, Sweden, where the 27-year-old actress had been shooting scenes for the upcoming film "Mammoth," said Martin Stromberg, a spokesman for film production company Memfis Film.

"She received the news at her hotel late last night," Stromberg said, adding he had not spoken to the actress after she learned of Ledger's death.

The actor's personal strife was accompanied by professional anxiety. He said in a November interview that "Dark Knight" and "I'm Not There" took a toll.

"Last week I probably slept an average of two hours a night," Ledger told The New York Times. "I couldn't stop thinking. My body was exhausted, and my mind was still going." He said he took two Ambien pills, which only worked for an hour.

A day after Ledger's death, at least six TV satellite trucks were parked on the block or around the corner from his Manhattan apartment, with a stream of TV reporters doing their standups. There were bouquets, letters and candles piled in front of the building.

A handwritten letter on plain white paper anchored by votive candles read:

"Heath, how could anyone hate 10 things about you. We couldn't find one bad thing about you. God bless your soul, you're in our prayers."